The freezing point on a thermometer is marked as 20° and the boiling point at as 150°. A temperature of 60°C on this thermometer will be read as

To find how a temperature of 60°C is read on the custom thermometer, we can establish a linear relationship between the standard Celsius scale (°C) and the custom thermometer scale (°Y).

Let us define the key points on both scales:
1. For the Celsius scale (°C):
- The freezing point of water is $0°\text{C}$.
- The boiling point of water is $100°\text{C}$.

2. For the custom thermometer scale (°Y):
- The freezing point is marked as $20°$.
- The boiling point is marked as $150°$.

The relationship between any reading on the Celsius scale ($C$) and the corresponding reading on the custom scale ($Y$) is linear and can be written as:
$\frac{C-C_{\text{freezing}}}{C_{\text{boiling}}-C_{\text{freezing}}}$

Substituting the known values into the equation:
$\frac{C-0}{100-0}=\frac{Y-20}{150-20}$

Simplifying the fractions:
$\frac{C}{100}=\frac{Y-20}{130}$

We are given a temperature of $C=60°\text{C}$. Substituting $C=60$ into our formula:
$\frac{60}{100}=\frac{Y-20}{130}$

Reduce the left side:
$0.6=\frac{Y-20}{130}$

Multiply both sides by 130:
$0.6\times 130=Y-20$
$78=Y-20$

Solving for $Y$:
$Y=78+20$
$Y=98°$

Therefore, a temperature of 60°C will be read as 98° on this thermometer.